Revert "math.fish: support floating-point maths"

This reverts commit 7cad0069e8.

https://github.com/fish-shell/fish-shell/issues/1723
http://superuser.com/questions/31445/gnu-bc-modulo-with-scale-other-than-0

This is why we can't have nice things.

share/functions/math.fish

@@ -7,13 +7,8 @@ function math --description "Perform math calculations in bc"
 				return 0
 		end
 
-		# Override the locale so that the output can be used as input
+		set -l out (echo $argv|env BC_LINE_LENGTH=0 bc)
-		set -l LC_NUMERIC C
+                test -z "$out"; and return 1
-		# GNU bc extension
-		set -l BC_LINE_LENGTH 0
-
-		set -l out (printf '%g' (echo $argv| bc -l))
-		test -z "$out"; and return 1
 		echo $out
 		switch $out
 			case 0